Integrated Screening and Antifungal Potential of Microalgae Extracts Against Botrytis californica

Increasing agricultural productivity to meet the growing population's food requirements has now become the main focus of scientific and policy-driven research. But the intensive use of synthetic fungicides has caused potential harm to humans and the environment. Microalgae are gaining recognition as promising sources of bioactive compounds for sustainable agricultural applications. The comparative antifungal potential of different microalgae using various polar solvents, and the study of molecular docking between major antifungal compounds obtained from microalgal extracts and fungal targets, remain unexplored. Therefore, the present study focuses on the antifungal properties of two freshwater microalgal strains (Tetradesmus sp. PV683316 and Scenedesmus sp. PV683315) isolated from aquatic ecosystems of Uttarakhand, India, against Botrytis californica. Microalgal extracts were prepared in different solvents, i.e., methanol (TdME and ScME), ethanol (TdEE and ScEE), and acetone (TdAE and ScAE), and screened for antifungal activity via the poisoned food technique. Morphological changes in B. californica were studied using SEM treated with the ethanol extract of TdEE. A diverse set of bioactive compounds present in microalgal extracts was identified through GC-MS. In this study, TDEE (100 µL/mL) showed up to 82.60 ± 0.83% mycelial growth inhibition of B. californica as compared to other microalgal extracts prepared in different solvents. The study also revealed that TdEE reduced the formation of conidia and conidiophores of Botrytis californica. Major compounds detected in GC-MS analysis of TdEE were benzyl-diethyl-(2,6-xylylcarbamoylmethyl)ammonium benzoate (29.27%), benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, methyl ester (15.06%), lidocaine (14.81%), benzoic acid 4-ethoxy-ethyl (7.95%), 2,4-di-tert-butylphenol (5.26%), and 1-(4-Ethoxyphenyl)propan-1-ol (3.28%). These findings highlight the potential of microalgae as eco-friendly sources in sustainable agriculture as antifungal agents for crop protection.